Telephony



-H. S. TURNER.

TELEPHONY -APP LiCATl0N FILED AUG.12. I915.

Patented July 4, 1922;

2 SHEETS-SHEET l IIEIIIHIIP H. S. TURNER.

TELEPHONY. APPLiCATlON FILED AUG, 12, I915 Patented July 4, 1922.

' 2 SIHEETSSHEET 2.

pes 'fiqetiei i ette -signe Patented July 4, 1922.

Application filed August 12, '1 91 5. Serial No. 45,232.

To all whom it may concern Be it known that I, IIUBERT Synnni TURNER, a citizen of the United'states, residing at Washington, District offiolum'bia, have invented certain new and useful Improvements in Telephony, of which the following is a specification.

' (1) "The present invention has for one of its principal objects the provision of means whereby the usual busy tests made on a called for line are dispensed with, thereby effecting a great saving in the operator"s time, an audible busy signal distinctive to the .operatingco-nditio-n of the called for line being sounded in the calling partys telephone receiver it an operator establishes a connection to a busy line, whereupon the calling party will replace his receiver .upon its .switchhook, thereby obtaining ,an autoniaticQdisconnection from the called for line, or iVi-l-lyvait until the called for line becomes idle, whereupon the busy signal ceases'to Ebe sounded in the receiver and the two lines are automatically connected, the called for partys call bell at the same time being automatically rung; the provision of means whereby it an operator establishes a connection to a busy line for which one or more calling parties, as, the ,case may be, are waiting, the described busy signal will be sounded in the operators telephone receiver, whereupon the connection will be taken down and reportmade to the calling party that one or more parties are already waiting upon the line in question; the pros vision of means whereby two or more icallingparties may wait for a busy line to hecome idle, being automatically connected thereto, successively,v in the same order, in which their lines were connected to the busy line; the provision of improved means for preventing a telephonic connection toa busy line and for allowing a calling party to Wait for a busy line to become idle; the adaptation ot all of the above features to trunking connections between exchanges; the provision of improved means for operating an operators transferable audible pilot signal, whereby the means for producing such signals are greatly simplified and rendered more eflicient in operation; and improved means for operating a subscribers and operators call recording system. Other objects will be apparent from the specification.

2) invention is particularly applicable some of its features to those telephone systems ot the semiautomatic type, to which type, however, the invention is not to be restricted. I i v (3) In the following description reference will be had to my U, S. Patent No. 1,128,262, and my co-pending application, Serial No. 11046, as the present application in some of its aspects consistsin improved means for accomplishing the results des ib d the e n i i l) order to more fully describe my invention reference will be had to the accomp n in f re-Win or ng" a p of hi specification, and wherein: I

t F ure is a dia ram i lu ra g in n f th va i us fe tu e f y inventlon above mentioned, excepting the trunking system and the means whereby .two or mi reparties m y Wai for a bu line to come idle; Figure '2 a diagram illustrating a modification of the link connector illustrated Figure 1 and, in .bne form illustrating the means whereby two or more partiesimay wait for a busy lineto become idle; Figure 3 a diagram illustrating in one form a modification of this invention adapted for use in those exchanges where all incoming e ls ar flank d; Figure a diagram l trating in one forma modification of this invention whereby the features of the same are adapted to a trunking system; Figure 5, a diagram illustrating in modified form one of therelays used for preventing a telephonic ;connection to a busy line and for permitting a waiting connection to the same, and Figure 6, a diagram illustrating the means used wherebytlie disclosed operators audible pilot signals may be adapted for use with a standard form of link con nector circuit well known in the telephone art.

(.6) Referring first to Figure 1, A and AA represent telephone substations of a form Well known in the art. The removal of the telephone receiver at substation A closes a circuit for direct current through limbs -1 and 2 o-f-the substation line, thereby causing the actuation of line relay B. The path for said circuit being from battery C, through '3, 4, right hand winding of B, 5, 1, through the substation telephone ap ar'atus at A, 2, 6 and to ground 'tirough the left hand winding of 13. Therefore,

armature 7 of relay" B is attracted, estab lishing a circuit over the following path battery 0,3, 4,8, 7, 9, D, 10 and to tion of armature 11 ofrelay E establishes a circuit over the following path; generator to ground through primary 21 of induction coil G. The segments of commutator 7' of,

generator '15 are such that a currentof a fluctuating character is furnished, ,Therefore, primary '21 generates an alternating current in secondary 22 which is heard in the form of an audible signal by theioperae tor wearing head receiver H, due to the inclusion of the latter in a circuit with secondary 22 and windings 23 and 24 of opera tors repeating coil 1. As primary 21 may be of a high resistance, it can consistof a great number of turns, and as transfer and retransfer relaysM, O, and N, Z, which at times are in circuit therewith, are of a sensitive type which permits windings of low impedance and few ampere turns, very slight fluctuations in the. current flowing through said primary will. produce the required audiblesignal in receiver H.

(7) I have shown inthe center of theupper part of Figure 1, the complete apparatus common to each.operators position at the switchboard; tothe left and'right thereof, that part of said apparatus relatedto the i right and left positions'which is associated with the apparatus of the central position;

denoting the left position by adding a and 1 as exponents to the reference characters, and the right position by adding o and 3. At the left and right ofv the last mentioned positions, I have shown a part ofthe associated apparatus of the next positions in line, denoting the same by the addition of b and 2, and (Z and 4, respectively, as'expo-- nents to the reference characters;

(8)1n the preferred embodiment of invention 1 take all theline lamps located with their corresponding answering jacks on the left side of each operators position and connect them as ndicated by the w res at 25, and as described 1n relation to -l1nelamp D;while those located on the right side-of each operators position are connected, as

indicated by the wires at '26, and as now to be described in relation to linelamp J.

Lamp J is illuminated on the removal of the telephone receiver at substation AAin the same manner as described in relation to lamp D, the circuit being established over the following pathzbat-tery'C, 3, 27, 28, 29, 30, J, 31, and to ground through K. j Lamp J is illuminated, and pilot relay K actuated by the current flowing in this circuit. The

attraction of armature 32 establishes a circuit over the following pathzgenerator F, 33, 32, 34, 35, 36, 37, 38, 39, and if the operator at the next position to the right is on -duty,-then relay-L is actuated (as will be hereinafter described), therefore the path "proceeds byway of 40, 41, 42, 43, 44, 45, 46, relay M, 47, and to ground through 20 and primary 21, as described in relation to lamp I U f D. Therefore, the same audible signal is F, 12, 11, 1a, 14, 15, 16, 17, 18,19, 20' and produced in receiver H. However, the current controlled by pilot relay K has traversed transfer relay .M, which is actuated thereby. Therefore, should lamp D or any other lamp on the leftside ofthe central positionbe illuminated at the same time as lamp J, or any other lamp on the right side, the circuit for pilot relay E would be changed at armature 18 of transfer relay M, and the path for the current controlled by the sam e'would proceed byway of armature 18, 48, winding n of relay N, 49, to the operators position at the immediate left, and if the operator there is on duty, then relay L" is 3.0m

51 52 53 54 55 56 1a, 57 O" andthen by way of 46, M,'47,20 (corresponding to similar references' -at the central position) j and to ground through the primary corre-.- spondingto 21,. as shown at the centralpo. s tion. Therefore, the operator at the left or a position would receive the audible signal produced whenever lamp Dor other left side lamp of the central position is illuminated, provided lamp J or other right "side lamp is illuminated at the same time. There fore,said operator would attend to the call, while the operator at the central position wouldattend to the call represented by the right side'lamp, always giving preference to calls from the right side of that position, as the audible pilot signal from the .left side is automatically transferred, as described, and the callattended to by the operator at the a positionj -Resistance 14 in series with contact 13 of pilot relay E, and resistance35 in series with contact 34 0f pilot relay K are used for preventing the short-.cir'cuiting of the windings of any of jtheqlrelays N, Z,"

M or 0, when relays E o-r K are operated. (9)v Lamps D and J, corresponding to the a, operators position, are illuminated'by' the actuation of line relays- B and B in; the same manner asdescribed in relation to line relay excepting that the circuit for the lamps instead of passing through a pilot relay, such as E or K, is directly to the armature switches of relay L',,thereby eliminating the pilot relays. If this form is used, generator F is connected as shown to armatures? and 7 of line relays B and B At 58 and 59 are shown the connecting leadsof the corresponding lamps of that position. 1

(10) When the circuit from pilot relay E was transferred, as, described, (paragraph 8), lamp D had been illuminated, the actuation of transfer relay M, due to the circuit traced therethrough, would have transferred the circuit connections of said lamp to the next position at the left, in the same way that the actuation of transfer relay M transferred the circuit connections from pilot relay E. In the same way, it will be seen, the circuit connections of any left side lamp at a position are changed, provided a transferred connection has been made from the position at the immediate right. Therefore, an audible signal is sounded in an operators receiver by the circuit connections of a line lamp at the position to the immediate right in preference to a signal from the circuit connections of a line lamp at said operators own position.

'(11) The arrangement described in the preceding paragraphs, and to be described in the following ones, is purely optional, as the circuit connections of the transfer and re transfer relays controlling the circuits from theline pilot relays or line lamps, as the case may be, may easily be changed to give other combinations. The arrangement, as described, has been selected to illustrate the invention on account of it being considered the most efiicient means of obtaining adequate team-work among the operators at an exchange. As the left side'of a position at the immediate right of an operator is practically as convenient of access as said operators own position, the line lamps thereat as readily observable, and the answering jacks as easily connectible, said operator can attend to a call thereat in preference to a call at the position immediately in front of the operator, inasmuch as the latter will be attended to by the operator at the next position to the left.

(12) When the circuit from pilot relay E was transferred, as described (paragraph 8), if lamp J had been illuminated, or becomes illuminated subsequently, the actuation of transfer relay 0, due to the circuit traced therethrough, would have changed its circuit connections at armature 44, and the path for the current from lamp J would proceed by way of armature 44 60 61, 62, armature 63 of re-transfer relay N, and as the latter is actuated, due to the current flowing through winding 41, the path proceeds by way of 64, 65, 66, 51*, 52 53 54 55 and 56 to ground through primary of perators induction coil at the "0. position, over the same path as that followed by the circuit already traced through 56 at the a position. Therefore. it will be seen that if a transferred connection is made from the left side of the central position to the a position by the operation of a line lamp on the right side, the audible'line pilot signal connections of both sides of the a, position are transferred to the Z2 position, the operator thereat attending to .a call from either side, while the operator at the 0; position attends to the call at the left side of the central posi tion, the operator at the latter attending to the call from the right side of said position.

(13) When the last described transference of an audible line pilot signal from the a to the 7) position takes place, any audible line pilot signals which may originate on either the right or left side of the 7) position are transferred to the next position at the left, and so on in succession, are transferred the signals from all positions to the left. The circuit for this transfer being over the same paths as those already traced in relation to the central and a positions. In the drawing only the right half of the 7) position is represented, but for the sake of clearness, the circuit for the last mentioned transfer will be traced over the following path: from the pilot relay or line lamp, as the case may be, through 42*, 43 44 60 61 67, 68 69, 62 63 64, and 65, over the same path as traced for the transferred signal from the central position over wire 65.

(14) It will be noted that commutator f of generator F of position a consists of a lesser number of segments than commutator of generator F of the central position, and

as both generators produce a fluctuating curposition 0 has a commutator f of more segments than either f or Therefore, at the three adjacent positions the audible pilot signals are of a distinct character, an operator being able to determine by the ,charac ter of the signal whether the same originates at that particular position or has been transferred thereto from .citherthe left or right. Instead of using generators, as illustrated, interrupters connected to abattery may be used, as illustrated and described in my aforementioned U. S. Patent No; 1,128,262.

(15) At the central position, re-transfer relay N is shown as having two windings and a circuit has been traced through winding a which actuated said relay. The other re-transfer relays are shown without this double winding, as the same may or may not beused, as desired, it not being essential to the operation of the system. The purpose of this extra winding will now be explained. Referring to position 0 .(to the immediate right of the central one) when both pilot relays E and K are energized, current flows from generator F over the same circuit as traced from generator F and therefore the circuit controlled by pilot relay E is changed at armature 18 of transfer relay M as was the circuit at armature 18 of relay M of the central position. As the circuit connections between positions and the central one illustrate an alternative form, (whichmay or may not be used) to that between the latter and position a, the path for the circuit will be traced from armature 18 of relay 1v 3 through 18, 48, 49, 70, 54, 55,56 and proceeding through-relays N, O

' and M of the central position as already traced in relation to position a. Now should acall originate at the central position and pilot relay K be actuated thereby, the path for the circuit traced through armature 44 of transfer relay 0 would be changed from contact 45 to contact 60 and the path would. proceed as follows: 60, 61, 62, 63, .(and as re-transfer relay N is not actuated as was -relay N) 71, 57, 0 46, M 47 and to ground through the primary of the operators induction coil. The current passing through transfer relay O would actuate the same and the attraction of armature 44, would change the path of the circuit controlled by pilot relay K from contact 45 to contact 60 and thence by way of 61, 62,

nals, though in practice improbable of occurrence as it demands a simultaneous illumination of a right side lamp at the central characteristic of the central position.

position and a left and right side lamp at position 0, by the use of the extra winding as shown at re-transfer relay N, the eventuality is avoided, as when lamps D and J are simultaneously illuminated relay N is actuated, as described, (paragraph 12) and a call from the right side of position a is transferred to position. b. Evenv if such a winding is-not used, the duties of the oper-' ators concerned would nevertheless not be interfered. with. as seeing a left side lamp burning at position 0, the operator thereat would pay no attention to the audible signal ever, the'double winding on re-transfer relay N isjeasily provided for.

-(16) So far,it has only been explained how the audible pilot signals are transferred when one or more lamps: on both sides of a position are illuminated simultaneously. As different transferring means are employed for the audible line pilot signals when an operator is engaged in answering a call or completlng the same, this will now be fully explained. On hearing an audible pilot signal and seeing an illuminatedlainp l), for instance, the operator at the central position in- Therefore, the

serts answering plug-P of the illustratedlink '0 connector, in line jack Q, associated with the calling line,(@ and Q may be considered as rep-resentingansweringjacks and R and R multiple jacks of therespective lines), a circuit is at once established over; the following path: batteryC, 72,73, 74,75, winding r of relay R 76, S, 77, winding t of relay T, 78, 79, 80, 81, 82, 83,11, 84, 85and to ground through cut-off relay V. The consequent actuation of cut-off relay V opens the circuit through line relay B and thereby eX- tinguishes line lamp D controlled by the same. Relays T and S are actuated by the current flowing in the circuit traced through them, armature 86 of T being attracted and thereby establishing a circuit, the path for which is as follows; batteries C and C interrupter W, 87, 88, 89, X, Y,.90, 86,91, 78, 79, 8O, s1, s2, 83,11,84, andtoground through cut-off relay V The intermittent current allowed to pass through connecting relay X by interrupter 1V causes armature 92 to engage spring switch 89, thereby connecting battery C through wires 3 and 93 to connecting relay This current causes armature 92 to continue its-movement, thereby removing spring switch 89 from contact 88 and thereby removing from the circuit batteries C and C through interrupter W.

Qnly the described connection of battery 0 1s suflicient to. cause the top armature switches of relay X to'engage their contacts,

thereby establishing a circuit, the path for which'is as follows: battery C 94, 95, 96, 97, 9s, 99, 100, 101, 102, 103, 101,105, 106, 107 and winding t. in' multiple, 108, 109,

110, 2, substation apparatus at A, 1,111, 112,

113, 114,, 115,116, 117, 11s,.119, 120, 121, A, 122 and to ground through 123. Relay A which is shunted by condenser a to permit the passage of voice. currents, is actuatedby the current flowing in this circuit and another circuit is established, the path for which is as follows: battery C 94,95, 123,

relay N 57, O, 46, M, 47 20and 'to ground through primary 21'. As transfer relays' O 124, G 125, 126, 127,'Z, 56, winding a of will not produce an audible pilot signal in head receiver H, as the attraction of armature 44 of relay 0 would transfer said signal circuit from the right side byway of. 60,61, 62, 62, 63, 71, 57 0 ,46 1 17 and 20 1011118, operators induction 0011 at the 0 position; the attraction of armature 18 of relayM transferring said signals from the left side by way of 48,01, 49, 50, 51 52", 53 ,549, 55 56 N, 57 0, 46*, M, 4" and 20 to the operators induction 00-11 at the a.

position. Operatorls call recorder G is actuated by the current flowing through this circuit and as the same cannot actuate until relay A actuates, which, in turn, cannot actuate unless a connection is actually made to a line initiating a call; said recorder furnishing a bona tide record of the calls answered by the operator, there bein no way to- Ina-lie it record more than once for each connection made.

(17) Assuming that while the central op erator is engaged in connecting toa calling line, as described (paragraph 16), and assuming that an audible line pilot signal, as also described therein, is transferred to the a or 0- positions or to both, then as the respective transfer relays at said positions are actuated and as the same control the circuit connections for said signals originating in said positions, any audible signal originating in. either the a or 0 position is automatically transferred to the Z) position from the a one, and to the a? position from the 0 one. Said transfer, inv turn transferring the audible pilot signals originating in the b and cl positions to those nextin line, and so on.

(18) The N and Z r'e-transfer relays control the retransferring of the audible line pilot signals; or in other words; change the circuit connections, which are normally transferred to the right and left positions respectively from the two sides of a busy position, so that both sides are transferred to but one position according to Whether the left or right position is busy also. Therefore, retransfer relays N and Z of the central position being actuated, as described (paragraph 16), should transfer relayM of the next position to the right be actuated, the audible signal, which might betransferred thereby through armature 18 of the same, 48, 49, 70, 54 and 55 to receiver H at the central position, would be re-transferred through armature 54 of relay Z, contact 128, 129, 130 and 62 to the receiver at position (Z at the right of the originating position. In the same way, should transfer relay 0 of the next position to the left of the central one be actuated, relay N would re-transfer the signal to the next position to the left of the originating po sit-ion. I p

(19) Reference has been made and the circuits traced and described (paragraph. 17), for the transference of the audible sig nal circuits originating in one position to the next in line when a signal circuit is trans ferred to the former from another position, the explanation havingbeen made that an operator can always reach the left or right side or both sides, as the case may be, of the adjacent position, allowing the audible signals originating in that position to be, in turn, transferred to the next position. However, it is essential for the convenient working of the system, that this transference to a position shall not include a call originating in a position other than the adjacent one, provided the operator thereat is on duty, as it Would be difli'cult for an operator to reach over and beyond another operator to answer a call. This eventuality is provided for by separating the functions of the re-transfer relays from the functions of the transfer relays and limiting the functions of the two former to the re-transferring of the audible signal circuit connections and the two latter to the transferring of the signals originating in a position. The same thing is true when a position is busy; the audible signal circuit connections of that position are transferred to the adjacent positions, but the signal circuits transferred thereto are not transferred so as to pass intermediate position. Referring to the circuits, as described (paragraph 16,) and assuming that the central and the 0 positions are both busy, then the respective transfer and re-transfer relays are actuated and anaudible signal from the right hand side of the central position would be transferred from armature 44 of transfer relay 0 over the following path; 60, 61, 62, 63, 64, 65?, 66, 50, 51, 52 53, 54- and if the a position was idle would be sounded in the operators head receiver at that position. At the same time, all the signals originating at that position would be transferred to the Z) position, as the central one is busy. However, if the a position is busy also then armature 54 of relay Z is attracted and the path traced thereto would be diverted from contact 55 to 128, 129 and 130 where it unites again with 62. Therefore, such a signal circuit from the central position can find no path, provided the left and right positions are also busy, but a path will be provided for the same at whichever of the three cited positions first becomes idle, and the signal will be sounded thereat. The same being true in regard to the signal circuit from the left hand side of the central position.

(20) In paragraph 16 a description was given of the means whereby the audible signals were transferred when a connection was made to a calling line. The circuit as traced therein through relays N,- Z, M and Q, and primary 21 of operators induction coil G receives steady current from battery 0*, therefore. no alternating current is produced in secondary;22 from this circuit, as was formerly produced by the current from the generators. As the circuit from substation A was traced through windings 96 and 123 of operators repeating coil I and as said secondary and operators headreceiver H are in circuit with windings 2'3 and 24 of said coil, conversation may take place be tween substation A and the operator. The path for the operators talking circuit is as follows: battery C 94, 95, 123, L, 131, 132, 133, H, 134, 135 and to ground through primary 136 of the operators induction coil- G.

Transmitter H and primary 136 are shunted by condenser I, the arrangement shown being well known in the art, there being but one difference, namely, the winding of relay L acts as a substitute for the retardation coil generally used to impede cross talk in the transmitter circuit. It will be readily understood, however, that instead of making relay L of the required impedance, the usual retardation coil might be used in series with said relay.

, (21) On obtaining the number with which the calling party desires to be connected, the operator inserts calling plug P in multiple jack R of the line in question.

137 disengages spring switch 138, the latter becomes engaged with contact144. There-' fore, the path for the circuit through winding a of relay U now proceeds through winding a of the same, wire 72 and to ground through battery C; Therefore, armature 73 of controlling relay U remains disconnected from contact 7 4 as long as calling plug P remains inserted in multiple jack R. The disengagement of armature switches 102 and 117 from spring switches 103 and 116 of relay S, opened the circuit through operators repeating coil 1, as de scribed (paragraph 16). Therefore, relay A, which controls the actuation of the transfer and re-transfer relays is de-energized, as are the latter, and operators head the 0 position.

receiver H will. again receive the audible line pilot signals originating in'the position, or transferred thereto. v

F (22) As described hereinbefore, the audible signal circuits have operated when all "the illustrated positions were 'occupied by their respective operators. Whenever a position is vacated, the operator thereat, in order to disconnect the transmitter (shown diagrammatically at H) withdraws plug W from its corresponding jack, and as jack spring 132 is thereby disconnected from ground through 133, H, 134, 135 and 136,

there is then no path for direct current through relay L. Therefore, the latter is de-energized and releases its various armatureswitches. This condition is shown at Therefore, the changes in the circuit connections caused thereby will be followed in relation to that position. The engagement of armature switch 37 of relay L with contact 145, changes the path of the circuit for the audible signal controlled by pilot relay K so that the same now proceeds by way of 146, 41, 42 and to armature 44 of relay 0, from whence 1t proceeds, as described (paragraph 8). If this position had been vacant also, then instead of the path having been 42, 43 and 44,

it would have been 42, 147,146, 41 and 42,

and thence according to whether the a position was vacant or not. Therefore,it will be seen that from any vacant position the audible signal circuits are transferred towards the left, and will be sounded in the operators receiver at the first occupied position. The transference to the left from a vacant position is of course purely arbitrary, and can, be towards'the right if desired. v 7 T (23) Assuming that the central position is occupied, and that current is passing over the path, as described (paragraph22),from the 0 position through armature 42 of relay L, 43, 44 and thence by way of 45, 46, and relay M to ground by way of 47 20 and 21, then relay M-would be actuated, and the circuit connection controlled by pilot relay K, as described (paragraph 8), through ardeenergization of the latter, from contact 40?, to, contact 148, and thence by way of 149 and attracted armature 18, to the next position at the left. The transfer of'the" calls from the left handsection of the central position takes place also inasmuch as r said wire 41. Armatures 151 and 152 con- -mature 39 of relay L is changed, by the engaged contact 150 which is connected to trol the connection of the leads 101and.

118Jfrom the connecting means associated with the various link connectors at the position. 'They have nothing to do with the described audible signal circuits and may be dispensed with'if desired, in which event lead 101 a would be" connected directly to winding 96 of operatorsvrepeating 'coil I and lead 118 connected direct to relay A.

The advantage in using theconnections as illustrated is that said armatures disconnect said loads at an idle position from contacts 98 and which are connected to said windings of the operators repeating coil at that position and connect the same to con tacts 153 and 154 which areconnected to, said coil at the next position by wires 15.5

and 156. If'that position is vacant the same are connected in the same way to the coil at the next position, and so on. Therefore, an operator can attend to a transferred call from any vacant position and use the link connectors thereat without having to change the transmitter or head receiver con necti'ons.

(24) As there are some slight differences between the connections controlled by the armature switches of relays L and LP, and those controlled by the corresponding relays L, L and L the differences will now be explained. Theform used in the latter are intended for use where the operators posit'ions are always vacated in a regular manner froni the right towards the left, or vice versa, as the'case my be. The form shown in relays and L being used when the positions are vacated, regardless of order, as the same provide means for, transferring the signals originating at a position to the right of a vacant one, to a position to the right of the originatingposition, something which is unnecessary to do, if the first mentioned way of vacating positions is followed. It will readily be understood that the two forms may be combined to produce other transferring combinations.

Assuming that the 7) position is vacant, and the a position occupied, the audible signal circuit controlled by armature 18 of relay M is transferred to the b potion.

sition by way of contact 18 and wires 49 and 50 'As armatureswitch 51 of relay L is engaged with contact 157 instead of 5 2 the circuit is transferred to the next position to the right of the a position. The path for the same being as follows: 157", 158?, 129 130", 62, and over the path to ground, as described (paragraph 15).

(26) Assuming that the a position 'is the vacant one, and the 5 position is occupied, the audlbl'e signal circuit controlled by armature 14E of relay 0- is transferred to the a position by way of contact and As armature switch 68 instead of 6.0 the circuit is transferred to the next position to the left of the posi- The path for the same being as fol lows: 159 16f) and 16 1 to the 51 armature switch of said position. The engagement of armature switch. 42 of relay L with contact 147 connected to wire 162 and armature switch 16* with contact 163 transfers the audible signal circuits from the a position to wire 16 1 and thence to the b position.

If visual pilot signals are desired, then lamps may be connected in series with the normal contacts of the transfer and re-transfer relays, as indicated at the 0 position by the lamps connected by the dotted lines. If the audible signal is not desired ii-h" connection therewith, then wire 20 would lead direct to ground, and a source of steady current could be used instead of generator F (27) 111 paragraph 16 was described the means used for establishing a telephonic connection between a calling party and the operator, and in paragraph 21 was described the means used for disconnecting the operator when a connection is made to a called for line, namely, the de-energization of relay S. However, when armature switches 1O2 and 117 disengage spring switches 103 and 116, engagement is first made between said spring switches and contacts 166 and 167, which are connected, respectively, to windings 168 and 169 of the link connector repeating coil. Therefore, current from battery C still flows through limbs 1 and 2 of the line of substation A, and consequently supervisory relay T is maintained actuated. The current flowing through the circuit traced through winding 1 or ringing relay R as described (paragraph 16), is sufficient only to cause armature 170 to engage spring switch 171, without causing the latter to engage spring switch 172, and contacts 173 and 174:. Therefore, the insertion of calling plug 1? in multiple jack R, as described (paragraph 21), established a circuit which was not described therein, the path for the same being as follows: battery C, 3, 93, 92, 175, 176, Y, 178, winding 1" of ringing relay R 182, 170, 171, 139, 141, 142, 143 and to ground through V. Cutoff relay V is actuated and opens the connections to line relay B as described in relation to line relay B. The current flowing through winding 1" of relay R is sufiicient to completely actuate the latter and the engagement of spring switch 171 with spring switch 172, establishes another circuit, the path for the same being as follows: batteries C and G TV, 179, 180. 181, Y X, 172 and to ground over the path already traced through spring switch 171. The intermittent current allowed to pass through connecting relay by interrupter causes armature 183 to engage spring switch 181, thereby connecting battery C- through wire 184k to connecting relay X. This cur rent causes armature 188to continue its movement, thereby removing springswitch 181 from contact 180 and removing from the circuit batteries C and C through interrupter 1V. Only the described connection of battery C causes the top armature switches of relaay .Xto engage, their confacts, thereby establishing a circuit, the path for which'is as follows: battery C D 185., 186, 18. 188, winding t of relay T, 189, 190, 191, 1.92. 193, 194., 2 195, 196, 197, 1". 198, 199,200., 201, 202 and to ground through 203. Another circuit is established in branch relation to the former, the path for which is as follows: generator A G D and G and the full operation of the automatic ringing system, illustrated in the accompanying drawings.) The current from ringing-generator A flowing over this circuit actuatescall bell 195 at substation 'AA and as the return path to ground is through winding'203 of the repeating coil, the calling party at substation A receives an audible signal through the telephone receiver thereat. Condenser 197 at substation AA does not allow a circuit to be closed through winding t of calling supervisory relay T, which is sufficient to energize the same when the brush of interrupter D engages the metallic segments thereof.

(28) Interrupter D may be connected as illustrated to a battery of lower voltage than battery 0, which furnishes the talking current to the substation, thereby preventing any slight tendency of relay T to be partially energized due to the intermittent direct current flowing through the circuit including condenser 197. However, said interrupter can be connected to battery 0*, if desired, as relay T can readily be adjusted so as not to respond until condenser 197 is short circuited by a low resistance path when the receiver at substation B is removed from its switchhook.

(29) When the called party responds and the just mentioned low resistance path is formed, relay T is actuated and a low resistance shunt is formed around ringing relay R -and lamp Y from battery C over a path as follows: battery C, 184, 183, 181, ar-

; mature switch and alternate contact of relay T, winding 25 of relay T, winding g of relay G completing the shunt. Due to the extremely low resistance shunt thus formed, relay R is deenergized and when armature "170 disengages sprlng switch 171,-the shunt 'is removed and the circuit opened through relay R As interrupted D furnishes an intermittent current, the armature switch of relay'T might make and break its connection with its alternate contact and therefore 1 closed and opened.

"special adjustments of relay R 130 obtain its the shunt circuit might be intermittently As this might need de-energization when so shunted, the use of winding 25 is preferred, as the energizatlon of the same by the steady current from battery C, prevents the vibration of the former.

However, I find that relays T andR can be so made and adjusted as to operate as desired without the use of winclin t (30) Connecting relay %i. is not de-energized with ringing relay R asa connection 'from spring switch 172 to contact 1 12 of'calling plug P was madewhen armature183 of relay Xwasfully attracted. Therefore,

a circuit was closed overa path as follows:

172, 209, 210, 211, 212, and 213 to contact 142. Resistance 209 is such that when the shunt is formed,'as described (paragraph '29), enough current still flows through resistance 209 and relay X; tomaintain the latter actuated. The purposeof using resistances 182 and 209, is to prevent. the forming of a low reslstance shunt around other relays corresponding to other link connectors which may be connected to linejacks of lthesame its normal contact also, which is connected to said contact 214, winding t of super of battery C over the same path, and as said contact is made before armature switch 186 dlsengages spring switch 187, thecircuit is uninterrupted through said winding.

(31) Telephonic connection is now established between substations A and" AA, and

when either party desires disconnection from the other, it can be brought about independent. of the other party, and the {continued engagement of the link connector with jacks Q and B. At thev sametime either party visory relay T isconnected to the live pole will be automatically restored to'the 'control of their respective line signals, andtheir lines'released so that other'telephonic' connections may be made thereto. F

(32) When the receiver at substation A is replaced'on its switchho'ok, the circuit for direct current through limbs 1 and 2 is opened, and winding t of answering super-.

visory relay T is consequently: deenergized and a short circuit is formed around connecting relay Xand supervisorylamp Y, thereby causing the. de'energization of said relay. The actuation of relay X, when connection was made to the calling line, as de scribed (paragraph 16), made a connection to'contact 81 of answering plug P in branch relation to that madethrough wire 90, armature 86 and contact 91 of supervisory relay T. This connection was made over-thefoL' lowing path: 81, 80, 217,- 218, 219, 220 and 221. Therefore when said armature 86 disengages contact 91, relay is not de-enerby wire 222 to spring switch 89. As soon as spring switch 219 disengages its contacts, current ceases'to flow ov'erthispath. Resistance 221 is inserted to prevent acorrespond- V ing short-circuit of other relays of other link connectorswhioh may be connected f'tO line jacks of the same line, as} hereinafter idle-. '7 0 scribed; This means for deenergizing-relay X 18 preferred, as in practice it Wlll be found that supervisory relay T,- being of a necessarily sensitive type, is apt to momentarilyrelease armature 86 from contact 91if said relay accidentally receives a ar or blow. a As;

- this might deenergize relay X if there were no other connecting-means to contact 81 of plug P, and consequently disconnect the call ingand ca'lled' parties, I have illustrated and described the aforementioned means 'whereln 1 -"-armature 86 must notonly disengage-contact 91, but engage its-normal contact before deenergizing relay X. When spring switch 219 of relay X disengages contacts'218 and 220, battery current is cut off from contact 81 of plug P, therefore, cut-off relay V is tie-energized, restoring:linerelay B to the "control of substation A. 1. Gurrentnsprevent "windingt of relay T, relay S'an'd winding 1' consequently would'have tie-energized the same, thereby-cutting offthe impression of ringing current upon'call bell 195 of substation AA. If this had taken place, the

engagement of spring 'switch 172 of relay R with its normal contact would have formecha short-circuit around the winding of lamp Y and connecting relay X, and, therefore, would also-de energize the latter. This short-circuit is formed over the 'following path: said normal contact, 22 1, 225, and the armature switch of relay T. As soon as spring switch 211 disengages itscontacts, current ceases to flow over this path. Battery current is thereby'cut" off from contact 142 of calling plug P except the small amount allowed to pass through the two windings of relay U, which together form a very high resistance. here'- fore, cut-off relay V is de-energized, and line relay B restored to the control of substation AA, as said relay V cannot main tain itself actuated bythe current allowed to pass through relay U.

(3 1) W hen the called for-party replacesthe receiver at substation AA on its switch-.

hookafter-having responded to a call, winding 25 of supervisory relay T is consequently de-energized, and the armature switch falling back andengagingcontact 225 de-energizes connecting relay X in'the same manner as-described (paragraph '83);

(35) The -disengagement of armature switches 105 and 115 of connecting relay X from contacts 106 and 114., and 202 and 191 ofconnecting relay X from contacts 201 and 190 disconnects the link connector repeating coil from'connection with the contacts of plugs P and P, all the talking and operating circuits of said link connector being thereby restored to their normal open condition, only onelinkconnector circuit remains closed, namely, that through controlling relay U, which on account of controllingbut one contact, may be of an extremely sensitive type, allowing the con1- bined windings to be of an extremely'high resistance. In fact the resistance may be such that if several; idle link connectors are allowed to remain connected to difierent 'multiple acks associated with "the same line, the multipledresistances of all the relays U, will not besufiiciently low to allow relay V to remain actuated, when the'party' at substation connected to said line has replaced its receiver upon its switchhook.

(36) The automatic means by which telephonic connection to a busy line is absolutely prevented, and the means whereby an operator or a calling party can so wait on abus-y line that atelephonic connection will be established only when the line becomes -idle, 'will now be described. YVhen connecting' relay X ofthe' link connector (referred to hereinafter as link connector one) is actuated as described (paragraph 16), a connection was made that has heretofore not been described. 1 This connection is that of interrupter H to spring switch 219, by

way ofwire 226,andthence by way ofcontact 218 and-wire 217 to contact 81 of answering plug P. Therefore, whenever the brush of interrupterI-I engages its metallic segment, current flows-from'batteries C and circuited, as the respective brushes of interrupters and H -engage their metallic segments atprecisely the same time and all the current allowed to pass from .ground throughrelays Vand U .to batteries G and Ci, naturally follows the-direct path of prac tically no 'resistancenoifered by wire 217. Therefore, relay X of linlnconnector two is not artially energized, and: armature 92 cannot be attracted aslong asrelay X of link connector one remains energized.

" (37) l/Vhenconnectingrelay X actuated, as described (paragraph 21),-a connection waszmade that has heretofore notbeen described." Thisconnection is-that of inter- 'rupter-I by way of 227, 5228, 229, 230., .211,

212 and 218 to contact' 142 of callingplug .P. Therefore, whenever the brush of interrupter I engages its metallic segment,

current flows from. batteries C and C 'di- V rectly to ground through contact 1&3 of

multiple jack R and cut-off relay V, Now if answering plug P of link connector two is inserted in avlinejack, such as Q, or R, connecting relay X of said link connector will alsobe short circuited, and not ener'-' gized', as described.(paragraph-36), as the brush of interrupter I engages its metallic segment precisely at the same time as interrupters H and W. WVhen ringingrelay R? is de-energized, as described*(paragraph 29);, then springswitch 229 of said relay. is disconnected from armature 228,. after first having been connected to contact 231 which byway of wire 282 is connected to interrupter H Therefore, a connection to a busy line by way of an answering plug P is positively prevented, regardless whether the busy line is a calling orcalled for line, as the connection to limbs 1 and 2 of the line is open at armatureswitches. 105 and 115 of relay X. There is: no mar ginal action of a relay or resistance of a divided circuit, used to obtain this result.

This feature is the specific difi'erence'in re lation to'this function between the present application and my afore-mentioned Pat 212 of relay X of link connector one re-' moves the short-circuit, as described (para graph 86), and connecting relay X, of link connector two would at once actuate. Therefore, supervisory lamp Y would be illuminated, indicating to the operator that the line was idle, and said actuation of relay X would prevent a telephonic connection from being made to the same line. 7 r

(39) If a calling plug P is inserted in a line jack ofa busy line, connecting relay X Y of the link connector two will be short-circuited, and therefore rendered inoperative.

in the same manner as described in relation to an answering plug P (paragraphs 36 and 37), inasmuch as contact 180 of said relay is connected by wire 179 to interrupter W as is contact 88 of connecting relay X. Therefore, a telephonic connection to a busy line by means of a calling plug P is positively prevented, regardless of whether the busy line is the calling or called for line, as thev connection to limbs 1 and 2 of the called nate the usual busy tests made by the opused in, the present invention as vdescribed" f lcalling party thatthe called for line is busy, O

forjconve rsational purposes When the call-1 111g" party hears 6li3l161' 0f SitlCl' signals, he

'forlineisopen'at armature switches 191 and 202 of relay X. g

(40') It has been mentioned that oneiof the objects of the present inventionis to elm'n erator on a called for line. Said tests are a necessary adjunct of the? telephone ex change connecting means heretofore used, as if not used much confusion would arise if a calling party was telephonically connected to" a line upon which a conversation wastaking 7 place, also secrecy between conversing zsubstations would be impossible, The means;

(paragraphs 36, 37 T38 and 89), eliminate:

of secrecy. Therefore, the operator :may connect directly to a called for line without previonslyytesting the same; However, some 2 means should be'providedl'for notifying theand this has been arranged. for in the. present invention in, such a way that the calling party receivesan audible signal'in the telephone receiver at substation A, provided an operator connectsvto a called for line which is being rung upon, or receives; an audible signal, distinct in character from the ringing signal, if the'called for line is being used may either replace his receiver, :thereby ree leasing his line, as described (paragraph 32), or may refrain from so'doing, and V wait for the called, for line to be released, as described (paragraphs 32, 33 and 34), whereupon the waiting party. will be automatically telephonically connected to the line waited upon and the call bell at a substation of the latter: will be.

rung. 7 v

11) Assuming'that a called forline has either a plug P or P of a link connector one inserted in a line jack, associated with that line, and that the connectin relay X or X has not been de-energized, then when calling plug P of link connector two is inserted in a corresponding linejack, connecting relay X will not actuate, as described (paragraph 39). As the'connection to limbs 1 and 2 of the called for line is open at armature switches 191 and 202, and contacts 190 and 201, of relay X, no telephonic connection is made with said line. However, ringing relay R will actuate as the same is not dependent on batteries C and C through one ofthe interrupters for its actuating current, but receives the same direct from battery 0, as described (paragraph 27). Relay U is also actuated, as its actuating current emanates from interrupter S, as described (paragraph 21), which interrupter, notwithstanding its connection to batteries C and C engages its brush at a different time interval from that'in which I 7 s0 the possibility of such confusion or such lack" link connector two is'not shortcircu-ited, as

is relay X of the same.- The actuation of relay U controls thereinoval of the opera.-

tors telephone set from connection with link connector two, and saidoperator has nothing else to do with the connection. However,

the non-actuation of relay X of ,link connector two, allows a small part of the current which flows from contact 142 of calling plug P of link connectorone through .con-

tact 82 or143 of line jack Q or R to be shunted from the path of ground through relays U and V or V, to ground over the following path: Said contact 82 or 143, corresponding contact of line .jack in, which calling plug P of link'connectortwo is inserted, contact 142'ofsame, 141,171,174,

233, 234,- 235, 236, 2.02 and to groundthrough 203., Resistance 234 ispreferably ininductive relation with the link connector repeat- 'ing coil, as shown. Its purpose is to increase the resistance of the described shunt circuit, so that enough 011171611111S not taken from cut-oft relay V- to de-energize the same.

However, said resistance is not absolutely essential. As the current impressedon contact 82 or 143 through link connector one is of a fluctuating character, due to the intermittent current from interrupters H ,Wor 1 as described (paragraphs 36 and 37), this fluctuating current flowing-in the described shunt circuit, induces a; corresponding alternating current in,windings*168 and 169 of the link connector repeating coil, which is heard as an audible signal in the receiver at substation A. If the busy line is being used for conversational purposes, the audible signal will becharacteristic to interrupter H If the line is being rungupomthe audible signal will becharacteristic to interrupters I? and J As the latter has more metallic segments than interrupter H the fiuctuations of current are, therefore, more rapid, and the audible signal produced of a differ- Yent character from that produced byinter- 'rupter H The number of metallic segments of interrupter J 1s purely arbitrary, as

.many may be used as desired, it being readily understood that the more metallic segments said interrupter contains, the greater the difference will be between thetwo audible signals; As the purpose of interrupter J is to furnish the ringing busy signal only, it may be connected, as illustrated, to'battery C or it may be connected to batteries C and C like interrupter I The purpose in connecting interrupter J as illustrated, is to effect an economy in current consumption.

(42) On hearing the busy signal, if the calling party electsto wait, then as soon as connecting relay X or X, as the case may.

be, of link connector one is released, as described (paragraphs 32, 33 and 34) the shortrelay X from contact 236, opens the audible busy signal circuit, and cessation of the same/and the substitution of the ringing audible signal, as described (paragraph 28),

is the waiting partys assurance that the waited upon line has been released, and. that a telephonic connection has been made thereto.

(43) When a waiting connection is madeto a busyline,as described (paragraph 41), a circuit is established-which has not yet been described, the path for the same being as follows: Batteries C and C interrupter P1237, 238, 239, 240, 241, 242, 173, 171, 139, 141, 142,143 and toiground through cut-01f relay V. Therefore, when a waiting connection has been established to a busy line by link connector two, should another calling plug P of another link connector (referred tohereinafter as link connector three) be inserted ina line jack of the same line, not only will connecting relay Xof the same be prevented from actuating, but controlling relay U, as well as the latter, will be short-circuited when the connection is made, inasmuch as interrupters S and P engage their respective brushes precisely at the same time interval. The action being similar tothat described (paragraphs 36, 37 and 39) in relation to interrupters H and W; As the actuation of said relay U is necessary to obtain the de-energization of relay S, and as the operators telephone set is not disconnected from the calling substation until rsaid relay is called for line. Therefore, the operator can" so inform the calling party, and either make a connection by means of calling plug P of link connector three to another line, or takedown the connection, according tothe wishes of the calling party.

- (44) Instead of the negative waiting busy signal for the operator, as described (paragraph 43), supplied by the lack of a click, a positive audible signal can be roduced in operators receiver H when a link connector three is connected to a busy'line. The circuit for this. signal is in branch relation to the audible busy signal circuit, as described (paragraph 41), and is over the following path: From wire 235 over wires as indicated by the dotted lines connected to the left contact of armature switch 117 of relay s, 117,118, 119, 120, 121, and to ground through 123. Therefore, the fluctuating current allowed to pass through.

I move 200, maybe made as indicated by the dotted resistance 284,has two paths'to ground, one

through winding 203' of the link connector repeating coil, and the other through winding l23 of operators repeating coil I.

Therefore, both the operator and the' subscriber would receive the" audible busy signal, and the operator would thereupon re plug P of linkconnector three from the line jack of thebusy line, and could not only inform the calling party that another,- .party was waiting upon said line, butcould.

state whether the called for party had answered or not, as the 1 audible signal would be either "the ringing or"talking one. 7

'-u Just as soon as relay X or relay X :of link connector oneis released, then relay,

'X of the waiting link connector two is energlzed, thereby disengaglng armature switch 242 from contact 241,1 which'opens the direct connection to interrupter P Therefore, another"waiting connection can be made to the same line, as the former link connector two has now become alink connector one, and relay U will not be short- .circuited when connection is made to the busy line. Also ringing current will'again' be impressed upon the waited for line, as described (paragraph27).

(46) Notwithstanding the fact that no busy test is necessary before connecting to a calledfor line, should the same nevertheless be desired, then a connection from tip contact 199 of calling plug P, through wire line which connects wire 200 to the same contact of armature switch 117 of relay '8 which produces the waiting busy signal, and a path to ground through winding 123 of operators repeating coil I, may thereby be provid'ed' as described (paragraph 44). Therefore the fluctuating current from the tested contact 143'line'jack R, as described (paragraph 41), would follow this path and provide the required busy test.

(47) Answeringsupervisory signal or series with relay R ,is energized whenever the calling party is waiting upon a busy line, indicating that condition to the operator. WVhen relayXfl'is also energized,

then signal or lamp ,Y is also energized.

Therefore, the energization of both Y and Y indicates to the operator that the called for line 'is being run upon. When the called party responds, T is de-energized by the de-energization of ringing relay R Therefore, the energization of Y alone, in-

Waiting I signal or lamp Y, on account of being 1n.

dicates to the operator that the called for line has responded. When the calledfor party replaces the receiver, irelay'X. is deenergized, and consequently Y? also. The de-energization of Y,- Y and- Yfiindicating may be removed.

the various operating conditions of the" link connector, and if desired, can remove plug Pf and inform the calling party that-there is no response from the'line being rung upon,

or that the line being waited upon is still busy, as the case may be; provided the signals are displayed for an "inordinate length of time. qTheoperator can do'this' without removing answering plug P from the'aanswering jack of the calling li'ne,"inasmuch 7 7c 2 to'the operator that both plugs P and P It will,,therefore, be seen that the operator is fully advised of asrelay U is deeenergized as soon-as c'alling plugP is removedflfrom line jaclr R;

and: consequently'relay energized, connect ing the operators setto the calling line.

(48) l/Vhen connectingrelay X act'uates,

armature switch 2481' engages contact 244,

which is connected by line 245 to contact 246, corresponding to relay Xfof the next link connector at the central operators position. Armature switch 247' is connected to the contact corresponding to 2460f relay of the next link connector, and thearma;

ture switch of the same corresponding to 247 connected similarly to the next contact.

tureswitches of the connectinglrelays X of all the link connectors .at a position are similarly connected, the same being represented by dotted llne 248. However, armature switch 250 of relay iX' of the last link connector is connected by wire251 to relay Z, and as armature switch 248 of relay X- of the first link connector is connected-by wires 252, and94 to battery Cfl when said armature switch engagescontact 244, 247 en-.

gages 246, 250 engages 249, and all the intermediate ones engage their respective con-.1

tacts, batteryfcurrent is impressed on relays Z, N, O and M, and the audible lino pilot signals transferred, as described (paragraphSlG) As the described connection to battery '0 takes placeonly when'all thelink connectors at a position are inactive use, it will be seen that in' such event no audible line'pilot signal will be sounded in operator"s receiver but-saidsignals will be transferred to 'the adjacent positions;v However, it will be readily seen that armature switch243 and contact 244 of relay'X All the correspondingicontacts andarmacan be done; away with, should such a function not be desired.

(49) Ft jis-asubscribers service meter,

which is actuated only afterthe called for substation has responded'to its calling signal. When calling supervisory relay T is' actuated, as described (paragraphi29), a circuit was traced through relay G The con-v sequent actuation of this relay establishes a circuit over the toll-owing path: battery C 253, 254, 255, 256, s0, s1, s2, 257,1"; 25s, 259, 260, and 261, to the other pole of battery C. Service meter relay U was actuated, as described (paragraph 16), therefore the current thus allowed toflow through winding 5/ of relay G maintains the same actuated after current (cases to flow through winding 9 of the same. Service meter F is also actuated by the same current and after its recording mechanism 258 has once operated, the same engages spring switch 85, and then removes the latter from contact 84-, thereby opening the circuit through service meter relay U. Armature 259 thereupon disengages contact 260, thereby opening the circuit through battery C. Relay G is consequently de-energized, and armature 254 disengages contact 255. The path for the circuit through cut-off relay V to ground, which was formerly by way of 85, 84, U and 83 to contact 82 of answer ing jack Q, is now by way of 85, 258, F and 257 to said contact 82, and as this latter path was established before the former was opened, the continued actuation of cut-off relay'V is not disturbed. It will readily be seen that the circuit through battery C is only closed for a very brief inter val,- namely, that necessary for the recording mechanism 258 of service meter F to actuate. Said battery is. oia preferably lower voltage than battery 0. Reference should he had to my U. S. Patent No. 1,147,347, for a full description of this service meter system, as the same is only described herein iureference to the slight modifications made necessary by the use of the intermittent direct currents through the interrupters associated with the connecting relays; 7 It will readily be understood that if service meter F is not used, the connection from contact 82 of answering all: Q to cut-oii' relayV, would be the same as that from contact 143 of answerin jack Q, to cut-oil" relay V, and that relay G would be eliminated.

(50) Reference is now made to Figure 2, in which the principal difference bet-weenthe same and Figure 1 is that two parties may wait upon a busy line, being telephonically connected thereto, successively, in the same order in which connection was established to the line jacks of the busy line. By extending the means illustrated in igure 2, and described hereinafter, and without departing from the principles involved, it will be evident that as many parties can be allowed to wait upon a busy line as may be desired, and that said parties will always be telep-honically'connected to the busy line successively in the same order as that in which connection was established thereto. An extrarelay such as connecting relay X for each extra party it is desired to allow or maynot be used.

.2 and the other figures.

to wait, is all that would have to be added to the link connector circuit illustrated in Figure -2. Some of the relay connections shown are different from those illustrated in Figure 1, being alternative forms which may It is understood that different combinations may be effected by combining some parts illustrated in Figure 1 with some of those illustrated in Figure Only those parts which vary from those described in relation to Figure 1 will be described, it being understood that those parts, shown but not described, function the same as similar parts in Figure 1.

(51) Relay S combines the functions of relay 8- and controlling relay U in Figure 1. When answering plug P is inserted in an answering jack, the circuit through winding t of answering supervisory relay T proceeds directly to battery C by way of 263, 264, 265, 266 and 267. The consequent actuation of relay T actuates connecting relay X in a similar way to that described (paragraph 16). However, it will be noted that armature 268 of relay X is connected by way of 269 and 270 to battery C as are interrupters VV and H instead of to a sepa rate battery such as C in Figure 1. The full actuation only of relay X causes an 'In'ature switches 273, 281 and 296 of the same to engage their respective contacts, thereby establishing a circuit from operators induction-coil I, over wires 118 and 101 in Figure 1, corresponding wires 118 and 101 in Figure 2, and then over the following path: 101, 271, 272, 273, 27a, 275, and winding i in multiple, 276, 277, answering jack; springs and substation apparatus, 278', 279, 280, 28-1, 282, 283, 284:, 285 and 286 to line 118. Relay A actuates, as described (paragraph 16), and the operators tel=ephon set is connected thereby'to the calling substation by way 10f wires 118 and 101. The dotted line from armature 281 of relay X and the contact connected thereto of spring switch 285 of relay S represents a connection that may be used if it is Wished 'rents offered by winding 288 of the repeating coil. When calling plug P 'is inserted in a multiple jack, a circuit is established, the path for which is as follows: battery C 5, 287, 288,290, 8", 291, 292, and to ground through the cut-off relay of the called for line. The intermittent current from interrupter S causes armature 293 to engage spring switch 289, and assaid armature 'is connected direct to battery C by wire 267, said armature continues its movement and removes spring switch 289 from contact 288, thereby eliminating interrupter S from the circuit. Spring switch 264 is disengaged from contact 265, thereby opening the circuit through winding 29* of relay'T. The

f 302, and at the sameti'me allow winding engagement of armature switch 306 with spring switch 272 first makes a connection from'the same by way of wire 307- to wind- .1 g;.-308 of the link connector repeating coil, and then removes 27 2 from engagement with-contact 271. The engagement ofarma j ture switch 309 with sprnig switch 285, first makes a connection from the same by'way of wires;310 and 3l1to ground, and then removes;285 from engagement with contact 1286. Therefore, the calling substation line is disconnected from the operators repeating coil, andconnected to that of the link ,-.connector. It will be readily understood mains actuated as longas calling plug P remains inserted in a link jack, the described circuit changes are maintained for that periodw'f q (52) Another circuit is simultaneously es -tablished with that first described (paragraph 51), the path for which .isasfollows: Battery C 294,;g 295, 296, 297, 298, 0 ,299, 300, 30-1, and thence to ground, over the same path astraced from the upperterminal of winding 3 of relay S Ringing relay R is actuated, and armature 302 engagingthe,

vc'ontactconnected to wire 299, establishes an-l other path to ground from said wire, as fol-; lows: 302,303, 304, 305 and 292 to ground,

throughthe cutoff relay. As armature 302 engages said contact before armature301-of evade any possibility of relay S actuating previous ,to said engagement of armature to be of [as high a resistance asthat ofrelay'U-. in Figure-'1, inasmuch as it remains in circuit after the parties have replaced theirreceivers as does said relay U, a con.-

nection may bemade to said winding 3, as

indicated by the dotted line connected to the second contact of armature 302 of relay R Thev complete windings is then such that relay S is not actuated until the upper por- ,.tion is short -circuited' when armature 302 engages said contact.

' 53) The engagement'of armature 302d ringing relay R with the contact connected to the upper terminal of winding 00 of relay Xt, establishes a ground connection through the same, which continues by way of 312, 313, 314,315 and interrupter WV to battery C Consequently, armature 316, which is connected to the same battery by way, of. 317.,

318, Y 319 and 320, engages itsfspring switclnestablishing a circuit,the path for which continues by way of winding m 321, 22 and 292'to ground; Therefore, relayrX 'isfullyactuated- .7 (54 ):Another circuit is established with that described (paragraph 53) when armature 302 of relay R engages the contact con-.

nected to the upper terminal of winding m to the same battery by way of 328,318,;Y

319 and 320) engaging its spring switch,

establishes a circuit, the pathfor whichcon- 1 tinues by way'of winding m 321,322 and 292 to ground. Therefore, relay X is fully V actuated. g a

(55) Armature switches329 and 330 of relay X? correspond in function to armature switches 202 and 19-1 of'relay X in Figure 1; However, their respective contacts 331- and 332, are connected to armature switches Y 333'and 334 of relay' X which must engage their respective contacts 335and 336,-b'efore the connection is made to contacts 337and 3380f calling plug P Therefore, both relays X? and X must be actuated before a telephoni connection can'be'n ade to the called for line. a

' (56) When: the called party responds, calling supervisory relayT? is actuated, as described (paragraph 29), and armature 305 disengaging. contact 30.4, opensthe'circuit through rimgingjrelay.QB by wayjof. 303 and ,302. Therefore,; said relay is: de-ener gi'zed and changes the circuit connections fromthe called for line from the ringing V w "generatorto the repeating coil,-as described relay S? disengages contact'300, the circuit through relayR ismaintained In orderto (paragraph 30).: Connecting'relays 'X and K are not deenergized as the connections ioo Y from windings 049' and 0'0 to ground are through wires 321and 322, direct to contact 292 of callingiplug P Therefore, tel e} j phonic connection is =now' established v be;'

tween the calling and'ca lled for substations.

QWllGIl the receiver atfisubstation Al isreplaced and answering supervisoryfrelay T 1s consequently de-energized, connect ng 're-" V lay X isshort-circuited and de-energized,

when armature 339 of re'lay T engages con- 1 V tact 340, inasmuch as wire 341 connects lamp Y ,by.way of 340,339, 342,343, 344, 345,343 V and 347, directly to ground, through contact 348 of answering plug P and the cuteoflf re lay. Relay X differs from connecting relay X in Figure" 1, in this particular, inasmuch as lamp Y 3.035.4 4. substitute for resistance 221 of the latter. 71f relayfX had been de-H' V energized previous to the response of the called for party, the 'dis-engagenient of armature 296.1fro1ncontacti297 would have 7 opened the, circuit through winding r 'of, ringing relay R and the relay would be de- I 125 energized, thereby cutting joif .the' impre ssion of ringing current upon the lineof the called for substation. If this @had taken: place, the engagement of armature 302 with. :j contact 349 would have short-'circuitedwindin s w and 90 .of rela and inas= much as the battery current through lamp Y would have had a direct path to ground through the cut-off relay by way of armature read de-ener ized conectin rela s X and X are de-energized, as described (iaragraph 56). is restored to its normal condition, as described (paragraph 35). Relay S which, as hereinbefore mentioned, combines the functions of relays S and U in Figure 1, is the only relay which remains actuated after both parties have replaced their respective receivers. As described (paragraph 52), the upper part of winding 8 maybe of so high a resistance that it prevents the actuation of the relay until it has been short-circuited, nevertheless, having once actuated, said relay will remain actuated after said short-circuit is removed when relay R is de-energized.

. (58) The functional differences between Figures 1 and 2, in relation to the descriptive matter contained in paragraphs 36 and 37 will now be described. The current from interrupter H (corresponding to H in Figure 1) passes by way of 351 through the upper winding of relay X and wire 352 to spring switch 345 (corresponding to 219 in Figure 1). In Figure 1 the interrupters are connected to batteries C and C while the windings ot the connecting relays are connected to battery 0, therefore said inter rupters do not short-circuit said windings. As the form used in Figure 2 is intended to do away with the necessity of two batteries, some means must be used to maintain the rela sactuated when the metallic .segments of t e interrupters engage their respective brushes. Therefore, the upper windings of relays X and X and the lower windings of relays S B and X are of an extremely low resistance, thereby forming a low resistance shunt, which is practically the same as the short-circuit, as described (paragraph 36), yet at the same time they are such that the relays are maintained actuated when their other higher resistance windings are therebypractically short-.circuited. As relays S and R are connected to battery 0,

interrupters P and S (corresponding to P and S in Figure 1) are also connected thereto. Interrupters I and J correspond Therefore, the link connector to interrupters I and J in Figure 1,- but the circuit from the same, by way of wire 353, through armature 354 and spring switch 355 of ringing relay R (corresponding to 228 and 229 of relay R in Figure 1) is "form shown in Figure 1 may be used.

(59). If a calling plug 1 is inserted in a line jack of a busy line, connecting relay X (corresponding to connecting'relay X in Figure 1) of the link connector two will be virtually short-circuited, as described (paragraph 39), inasmuch as contact 314 of said relay (corresponding to 180 of'relay X in Figure 1) is connected by wire 315 to interrupter W However, relay X is actuated as winding :20, which is connected to interrupter U which engages its brush at a different time interval from the other interrupters, is not virtually short-circuited by the corresponding interrupter V a connec tion from said interrupter, by way of 360, 361, 362, 363 and 364, being broken when spring switch 358 of relay X of link connector one disengaged contact 364. As the connection to the limbs of the called for line is open at contacts 331 and 332 of relay X no telephonic connections is made to said line.

(60) Assuming that a called for line has either a plug P or P of a link connector one inserted in a line jack associated with that line, and that relay X or relays X and X have not been de-energized, then the action that takes place is similar to that described (paragraph 41). When calling plug P of link connector two is inserted in a corresponding line jack, relay X does not actuate, but relay X does, as described (paragraph 59). However, ringing relay R (corresponding to R in Figure 1) actuates as the same is dependent on current direct from battery C Relay S also actuates, as the same is not short-circuited. The actuation of relay S removes the operators telephone set from connection to the calling line. The subscribers busy signal when a connection is made to a busy line operates similarly to the one described (paragraph 41). However, in Figure 2, resistance 365 (corresponding to 234 in Figure 1) is shown as not being in inductive relation to the windings of the repeating coil, as such relation may or may not be used.

(61) The calling party may wait upon the busy line, as described (paragraph 42).

7 Relay X actuating as does relay X in Fig- 'ure 1.

i (62) When a waiting graph 60), the action that takes place differs from that described (pa-ragraph4c3). The

actuation of relay X and the non-actuation of relay X establishes a circuit over the following path: battery C interrupter V 360, 361, 362, 368, 364, 858,359, upper winding, of X, 322, and contact 292' to ground through thecut-ofi? relay. 7 The intermittent current traversing this upper winding prevents the de-energization of relay X when its windin 00 is' thus virtuallv short-cira y 'cuited by interrupterv However, ifa calling plug 1 of a link connector three is incuit over a path, as follows battery" C in-' terru Jter 1 s orin -switch connected there to and its contact, lower windings-of relays S and R 366, 367, 368, 369, and thecone V tact of relay R connected thereto, 2, 303,

304:, 305 and 292to ground through the cut- 7 off relay. The intermittent current flowing in=this circuit through the lower windings of relays S malt prevents them from beingshort-circuited,but at the "same time it prevents another relay S of another link connector from being energized.

(63) Assuming the line to be in the de scribed; condition, with a "link: connector one,

typifying a telephonic (connection; :a link connectortwo, typifying a waiting cone nection, and az link connector three typifying a" second waiting connection, all connected'thereto," then should a calling plug P of still another link connector be inserted V in a jack of the saine line,- notonly will reand X of the seine be prevented from'actuatlng, but relay S will also not actuate, due to the virtual ShOI'tfCllfCult traced in the last part ofthe;'precedlng ara 'ra 3h. Asthe intermittent direct curb V .7. n

rent flowing through resistance 365, as desmear (paragraph proceeds by way of armature switch 329 of relay R repeating 'coil winding 37 0', 284, 285, 286, and line 118 to ground through the operators repeating coil, the operator hearing the busy signal I would know that there were two parties alreadywaiting on the called for line,'and would therefore withdraw plug; P from the line jack, and notify thecalling party."

i then when relay X 01 relays X and X of '65. link'connector one are'deenergized, the virconnection is made to a busy. line, as described (para.

line in question.

coming calls are trunked: to otheriopertual: short-circuit, as described (paragraph 59),-around winding 0& of relay X -of link connector two is removed, and therefore, the

same at once actuates' Link connector two then becomes a link connector one, and the waited for substation call bell ls'rung again,

as described(paragraph 27). Relay X of link connector three thereupon actuates, as the virtual short circuit; around its winding 00 as descrlbed (paragraph 62),.1s removed when spring switch 358 of; relay 'X of. r Y

former link connector two, disengaged contact 364:. Therefore, link connector three now becomes a linkfconnector two, and will become, in turn, a linkconnectorone, when switch 367 'ofrelay' X of former link con-V nector three disengaged contact 368, the virtual short-circuit, asrdescribed (paragraph 63), is removed. Therefore, a. link con so the latter is released. NVhen} armature nector three may now be connectedto the (65) hough different from the corresponding iam scr,

the o connection of supervisory lamps or signals Y Y? and Y 1s 1 Y and Y in Figurel,, as described .(para+ graph 47)., thei function. is similar. As Y is connected to groundthrough the cut-off relay'by way of winding-sw et relay X and 92 0f relay Xt'in "multiple relationfto f each other, saidlamp will burn brighter, 1

when both of said'r'elays have actuated than it will when only one ,has actuated, as the circuit resistance is? thereby lowered. There- 1 fore, an operator'fcan tell whetheryarlink" connector-is in a waitingli or a' second waiting condition. It will beireadily unin series with the respective arniatures 316 derstood;thattwo lainps might be used,-each stitute for resistances 182,209Tand'221, in Figure i 1,?and described;@(par agraphs 30' and 32). V

' (66) "If; an atlas tie? 'iitest is required, 'a connection'is made from contact 338' of .calling plug' P fas indicated by dotted line 177, therebyzallowing the fiuctu p ating curi'entsi from a tested busy'jack to flow to-ground through 'theZoperatOrs a: peating' coil, as described (paragraph :46); (67 Reference is now made to" Figure 3, whichrepresents'a linkconnector which may be used in those'exchangeslwhere all inators. The insertion of answering'plug P in aline ack of thecallingline,establishes a circuit overthe following'path} battery 6?,

3'71, 372, s 373, 3 74, 375,. winding-" or re:

lay T 37 6,: 377,; 378, Y 37,9, [380, 381; and I 7 contact 382 toground throughthe cut ofi 1 '1 (64') Assuming the line to still be inthe';

V relay. 7 The intermittent? current' thus ajl-lf condition, as described (paragraph '62),"

lowed topass through winding .15 [causes 7' armature 381 of answering; supervisory, re

opening the circuit through wire 379. However, a path for said current is still furnished through the winding of connecting relay X and wire 383 to contact 382. Therefore, said relay is actuated as soon as the short-circuit through 380 and 381 is removed. The intermittent direct current from interrupter S causes! armature 384, connected direct to battery G through wires 385 and 371, to first engage spring switch 378 and then to remove the same from contact 377, thereby excluding winding t of relay T? and interrupter S from the circuit and substituting stead-y current for the intermittent. However, previous to said disengagement of 378 from 377, armature 384 also engages contact 386 and armature 387 engages contact 388. Therefore, a circuit is closed throughwinding t of relay T which maintains the same actuated. The path for this circuit is as follows: battery C 371, 385, 384, 386, 389, winding 25 and 390 in multiple, 39]., engaged jac'lrsprings, ,substation line and apparatus, 392, 393, 394, .388 and to ground through 387. Relay L is the same relay as shown at L in Figure 1. The only changes in the circuit connections of the same being those shown, it being understood that the other parts of said relay are as shown in said Figure 1. Therefore, the described actuation of connecting relay X also closes a circuit over the following path: battery C 371, 385,384, 395, 396, 397, 398, 399, 4.00, 401, 402, 403, H A; 120 and 119, representing similar references in Figure 1; 404, 405, 406, 407, 408, 409 and to ground through 387. The consequent actuation of relay A causes armature 126 to engage contact 127, and close the same circuit controlling the audible line pilot signals, as described in relation to corresponding references in Figure 1. As operators receiver H is in circuit with windings 396 and 408 of the repeating coil, conversation can take place between the operator and the calling party, who is connected to the corresponding windings 389 and 394 of said repeating coil. The primary associated with secondary 403 and the operators transmitter are not shown in Figure '3, the same being well known in the art, and are as illustrated in Figure '6. The winding of relay A when used as shown in Figure 3, is preferably of an extremely high resistance, so that but little direct current can flow through receiver H thereby avoiding the disagreeable click which is apt to be sounded therein when a large amount of direct current traverses the same. Condenser a, which shunts said relay-,rallows the voice currents to pass around said winding.

(63) The means whereby the operator communicates with the trunking operator, known in the art as the B operator, and referred to herein as such, is not described, as

the same forms no part of the present invention. WVhen the connecting operator, known in the art as the A operator, and referred to herein as such, inserts calling plug l in a trunk jack, a connection is made between contact 410 and ground. Therefore, a circuit is established over the following pat-h: battery C 371, 373, S 411, 412, 413, X, 414, winding 2/ of relay U 415, 416, 417, 418, 419, 420 and to ground through contact 410. The intermittent current flowing through connecting relay X from interrupter 8*, causes armature 421, connected direct to battery C by way of wires 372 and 371, to first engage spring switch 413, and thereafter disengage the same from spring switch 412, substituting thereby direct cur rent for the intermittent cur-rent. Due to the actuation of relay X armature switches 398 and 406 disengage contacts 399 and 405, and engage contacts 422 and 423, thereby disconnecting the operators telephone set from the calling line, and connecting the latter through the repeating coil to the trunk line.- Control-ling relay U is also actuated, when plug P is inserted in the trunk ack, by the. current flowing through winding a, which is of a very low resistance. 2

(69) When the party at the calling substation replaces the receiver, answering supervisory relay T becomes de-energized as current ceases to flow in winding 25 The engagement of armature 381 with contact 380 establishes a short-circuit around relay X by way of wires 379 and 383, thereby deener 'izing said relay. Current ceases to flow to ground through contact 382 of answering plug P" and the cut-off relay, when armature 384 disengaging spring switch 378, as the circuit through contact 377, winding 5 and contact 374, is opened by the attraction of armature 37 3, when relay U is actuated, Therefore, the cut-off relay is restored to norma and the line relay restored to the control of the substation apparatus. Arma-f ture switches 387 and 384 disengaging their respective contacts, open the circuits through all. the repeating coil windings, thereby disconnecting the connected lines from each other, armature switch 417 disengaging contact 416 opens the circuit through connecting relay X tocontact 410 of plug P thereby (lo-energizing said relay, Relay U remains energized as long as plug P remains in the trunk jack, as current flows through winding a which is of a high resistance over the following path: battery C", 371, 372, if, 419, 420 and contact 410 to ground. If a cut-off relay is used to form the ground connection at the trunk j ack,-the same does not remain actuated by the current flowing but one interrupter for furnishing the intermittent current is used. It will be evident that the means used in the connecting relays in Figures land 2 would be applicable to Figure 3, as the means used in the latter would be applicable to the former. When relay X actuates, spring switch 424 engages contact 425, which isconneeted by wire 426 to a point in the winding of relay X The resistance between said point and wire 383 is verylow, but is sutlicient to maintain the relay actuated, notwithstanding it forms a low resistance shunt or virtual short-circuit for the lower part of the winding or for the entire winding of another relay X of another link connector. As spring switch 424 is connected to interrupter S a connection to a busy line is prevented in the same manner as has'been described in reference to Figures 1 and 2.

(71) An accidental connection to a busy trunk is also prevented, as when connecting relay X actuates, spring switch 412 engages contact 428, and a connection is made from interrupter S as described in relation to relay X W'inding u of relay U is of so low a resistance as not to interfere with the virtual short-circuit, and at the same time maintains said relay actuated. Therefore, should plug P be inserted in a jack connected to a busy trunk, relay X would not actuate and acircuit for the fluctuating current, as described (paragraphs 40 and 41), would be established over the following path: 410, 420, 429 430, 431, 432, 433, 434,

435, 408, 409 and to ground through 387. The fluctuating current thus allowed to How through resistance 435 and repeating coil winding 408, produces an audible signal in operators receiver H and the receiver at the calling substation. Hearing this signal, the operator would withdraw plug P from the trunk jack in question. Resistance 435 is such that the desired signal is produced and at the same time the continued actuation of thecut-off relay is not'impeded.

('72) If an operators busy test is required, aQconnection is made from contact 423 of "connecting relayX, as indicated by dotted line 436, thereby allowing the fluctuating currents from the tested busy line to flow through armature 434 of relay X resistance 435 and to ground through winding 408 of the repeating coil.

7 (73) .If the operator wishes to beadvised when a line becomes idle she may insert anw swering plug P in a line jack, and when the same becomes idle, and consequently relay X actuated, supervisory lamp or signal Y will be energized, indicating the idle condition to the operator. The connection of this lamp, as shown, furnishes the resistance- (74) In Figure 4 I have 'illustrated'one form of a trunk line circuit, embodying the features of this system,'which may be used illustrated in the preceding figures. Some of the other trunk circuits which may be with any of the link connector circuits, as

adapted for usetherewith, are shown and" 7 described in my co-pending application Se-l rial No..11,046. All the link connector circuits illustrated would naturally require a ground connection at the trunk jacks, corresponding to that of the cut-off relay, in order to disconnect the operators set from the line of the calling party, and operatethe connecting relays. As it is one of the obj ects of the present invention, in relation to the trunk circuit illustrated, to eliminate the busy tests usually made by the trunk operator, and to provide the same, waiting means for the trunk circuits, as has been hereinbefore described, by preventing the connection of ground at the trunk jack'if the VB operator connects to a line for which a party is waiting, I am enabled to produce an audible busy signal in the A'operators' receiver, similar to that described when said operator connects directly. to such a line. This signal being produced automatically, without any action on the part of the B operator, the latter has merely to insert the trunk plugs in the jacks of the lines called for, irrespective of the operating condition of the line. It will thus beseen that the work of the B operators is greatly reduced and simplified, no busy back connections having to be manually made and taken down by the B operator. The changes produced in thelink connector circuits, when connect- 1 ing to a called for, line, via the trunk circult, are the same asthose -described when 1 connection is made direct thereto;

(75) The meansby which the B operator receives the number of the called for line from the A operator, is not illustrated, as

the same is well known in the-art, and forms no part of the present invention. On receiving the designation of the trunk line which is to be used, the A operator inserts the calling plug of the link connector in.

trunk jack Q As. contact 437 of the jack is not connectedto ground thro'ugh438 and 439, until relay V has actuated, the A operators telephone set is notdisconnected from the linkconnector; If this trunk circuit is 7 used with the described link connector circuits, then the described operators-busy test' connections for the latter are used, as illustrated, by dotted line in Figure 1, and descrlbed (paragraph 46) by dotted line 177 in Figure 2, and described (paragraph by dotted line 436 in Figure 3, and described (paragraphfl72). Therefore, the tip, contact ofthe plug insertedin trunk jackrQF, 

